Is the funeral prayer four rak'ahs without bowing or prostrating, or is it one rak'ah with four takbeers? And what is the evidence for that?

The funeral prayer consists of specific "takbirat" (utterances of "Allahu Akbar") without bowing (ruku') or prostration (sujud). It is not correct to say it is one rak'ah with four takbirat; rather, it is a prayer that includes standing with four takbirat.